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water use evaluation. Of all the surface water sites downstream of • <br />Seneca II-W, only Sites WSDS (Dry Creekl, WSSF3 (Sage Creek), and WSHF1 <br />(lower Hubberson Gulch) have their waters used for irrigation. <br />Parameter <br />manganese (CDOH, 5W, irrigation) <br />Number of Sites <br />6 <br />Review of this summary indicates that only one CDOH surface water <br />agricultural use standards were exceeded. The manganese standard was <br />exceeded at six sites: However, as noted previously in the-..ground water <br />discussion, the relatively low CDOH standard of 0.2 mg/1, according to <br />the EPA, applies to plants grown in acidic soils. In .alkaline .soils; as <br />arefound in the Seneca-II-W region, a more appropriate (EPA)- standard <br />would be 10 mg/1. The maximum manganese value for any surface water <br />site observed this year was 1.09 mg/1. Premining manganese-values often <br />exceeded the 0.2 mg/1 standard. <br />NPDES Effluent Criteri a~ (Permit No. CO-0000221). One NPDES effluent <br />criteria were exceeded this year. The acute Ceriodaphnia~Whdle Effluent <br />Toxicity (WET) test conducted on a sample from NPDES 016 collected on <br />May 22 failed. Tests performed o n samples collected on May 30 and June <br />9 both passed, indicating that the May 22 failure may have been <br />incorrect. <br />Surface Water Sunvna ry. Flows from Ponds 005 and 006 were 559 and 418 of <br />their historic averages. No flow was observed at Pond 009 this year. <br />Peak flows measured at stream sites were generally the lowest observed <br />since 1494. TDS values NPDES sites 005 and 006 are increasing, as are <br />TDS values at all three downstream surface water sites (WSHF1, WSDS, and <br />W55F3). Discharges are normally suitable for livestock, but sometimes <br />exceed water quality standards for irrigation. <br /> <br />20 <br />